U.S. patent number 6,828,272 [Application Number 10/149,173] was granted by the patent office on 2004-12-07 for catalyst systems for polycondensation reactions.
This patent grant is currently assigned to Equipolymers GmbH. Invention is credited to Rolf Eckert, Gunter Feix, Sarat Munjal, Marion Sela, Volkmar Voerckel, Jens-Peter Wiegner.
United States Patent |
6,828,272 |
Wiegner , et al. |
December 7, 2004 |
Catalyst systems for polycondensation reactions
Abstract
The invention pertains to new catalyst systems for
polycondensation reactions, for example for producing polyethylene
terephthalate. In accordance with the invention, complex compounds
with hydrotalcite-analogous structures of general formula
[M(II).sub.1-x M(III).sub.x (OH).sub.2 ].sup.x+
(A.sup.n-.sub.x/n).mH.sub.2 O are used, wherein M(II) represents
divalent metals, preferably Mg or Zn or NI or Cu or Fe(II) or Co,
and M(III) represents trivalent metals, for example Al or Fe(III),
and A represents anions, preferably carbonates or borates. These
catalysts can be calcinated and can be used in combination with
phosphorus compounds that contain at least one hydrolyzable
phosphorus-oxygen bond.
Inventors: |
Wiegner; Jens-Peter (Halle,
DE), Eckert; Rolf (Halle, DE), Voerckel;
Volkmar (Merseburg, DE), Feix; Gunter (Halle,
DE), Sela; Marion (Halle, DE), Munjal;
Sarat (Lake Jackson, TX) |
Assignee: |
Equipolymers GmbH (Schkopau,
DE)
|
Family
ID: |
26865642 |
Appl.
No.: |
10/149,173 |
Filed: |
October 25, 2002 |
PCT
Filed: |
December 07, 2000 |
PCT No.: |
PCT/US00/33386 |
371(c)(1),(2),(4) Date: |
October 25, 2002 |
PCT
Pub. No.: |
WO01/42335 |
PCT
Pub. Date: |
June 14, 2001 |
Current U.S.
Class: |
502/208; 423/600;
502/341; 502/342; 502/327; 423/629; 502/343; 502/345; 502/346;
502/344 |
Current CPC
Class: |
C08G
63/82 (20130101); B01J 21/005 (20130101); B01J
23/007 (20130101); B01J 21/10 (20130101); B01J
23/06 (20130101) |
Current International
Class: |
C08G
63/00 (20060101); B01J 21/00 (20060101); B01J
23/00 (20060101); C08G 63/82 (20060101); B01J
21/10 (20060101); B01J 23/06 (20060101); B01J
027/14 (); B01J 023/40 (); B01J 023/02 (); C01F
007/02 (); C01F 007/04 () |
Field of
Search: |
;502/208,327,341-346
;423/593,600,629 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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EP |
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56059864 |
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May 1981 |
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JP |
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61118457 |
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Jun 1986 |
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JP |
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02308848 |
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Dec 1990 |
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JP |
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09077962 |
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Mar 1997 |
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JP |
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09208683 |
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Aug 1997 |
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JP |
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WO 97/45470 |
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Dec 1997 |
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WO |
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03/004547 |
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Jan 2003 |
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WO |
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04/014982 |
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Feb 2004 |
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WO |
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Other References
Database WPI Section Ch, Week 200259 Derwent Publications Ltd., GB.
AN 2002-552784 XP 002226337 & JP 2002 155134 A (Toyobo KK), May
28, 2002 abstract. .
Cavani et al. "Hydrotalcite-Type Anionic Clays: Preparation,
Properties and Applications" Catalysis Today, NL, Amsterdam. col
11, 1991, pp. 173-301, XP 000537043 cited in the application pp.
175, 213-215. month not avail. .
Patent Abstracts of Japan vol. 1998, No. 01. Jan. 30, 1998 & JP
09 241372 A (Teijin Ltd) Sep. 16, 1997 abstract. .
Database Chemical Abstracts. Accession No. 133:151341. XP002163660.
Abstract. Vasnev et al. Vysokomol. Soedin., Ser. A Ser.B. vol. 41,
No. 11, 1999, pp. 1733-1738 month not avail. .
Spectrochimica Acta, vol. 49A, No. 11, pp. 1575-1582, 1993. "A FTIR
spectroscopic study of surface acidity and basicity of mixed Mg,
Al-oxides obtained by thermal decomposition of hydrotalcite". M.
Del Arco, C. Martin, I. Martin, V. Rives and R. Trujillano.
Departmento de Quimica Inorganica, Universidad de Salamanca,
Facultad de Farmacia. .
Journal of Molecular Catalysis A: Chemical, accepted Oct. 30, 2003.
"Heterogeneous basic catalysts for the transesterification and the
polycondensation reactions in PET production from DMT". M. Di
Serio, R. Tesser, A. Ferrara and E. Santacesaria. Dipartimento di
Chimica, Universita di Napoli Ferederico II, Naples,
Italy..
|
Primary Examiner: Bell; Mark L.
Assistant Examiner: Hailey; Patricia L.
Parent Case Text
This application claims the benefit of in ternational application
no. PC/US00/33386 filed on Dec. 7, 2000 which claims the benefit of
U.S. Provisional Application Nos. 60/170054 filed Nov, 16, 2000.
Claims
What is claimed is:
1. Catalyst systems for polycondensation reactions comprising
hydrotalcite-analogons derivatives of the general formula
wherein M(II): divalent metals, M(III): trivalent metals, and A is
selected from the group consisting of carbonate, borate and titanyl
anions in combination with a phosphorus compound containing at
least one hydrolyzable phosphorus-oxygen bond.
2. Catalyst systems for polycondensation reactions in accordance
with claim 1, characterized in that M(II) is Mg or Zn or Ni or Cu
or Fe(II) or Co.
3. Catalyst systems for polycondensation reactions according to
claim 2, characterized in that M(III) is Al or Fe(III).
4. Catalyst systems for polycondensation reactions according to
claim 3, characterized in that the hydrotalcite-analogous is
derivatives are calcinated at temperatures of 200.degree. C. to
800.degree. C.
5. Catalyst systems for polycondensation reactions in accordance
with claim 3, characterized in that the particle sizes of the
hydrotalcites-analogous derivatives are in the range of 0.1 to 50
.mu.m.
6. Catalyst systems for polycondensation reactions in accordance
with claim 1, characterized in that as the phosphorus compounds,
are selected from phosphoric acid esters or esters of phosphorous
acid.
7. Catalyst systems for polycondensation reactions in accordance
with claim 6, characterized in that the catalyst system is used in
the proportion, hydrotalcite analogous derivatives to phosphorus
compound, of 1:0.5 to 1:4.
8. Catalyst systems for polycondensation reactions in accordance
with claim 1 wherein the system is substantially free of
Antimony.
9. A catalyst system for catalyzing a polycondensation reaction for
making a polyester material comprising: a) at least one
hydrotalcize-analogous derivative consisting of a material
represented by the general formula:
wherein M(II) is a divalent metal selected from at least one of:
Mg, Zn, Ni, Cu, Fe(II) and Co; M(III) is a trivalent metal selected
from at least one of: Al and Fe(III); and A is an anion is selected
from at least one of: carbonates, borates and titanyls; and b) a
phosphorus compound containing at least one hydrolyzable
phosphorus-oxygen bond.
Description
The invention pertains to new catalyst systems for polycondensation
reactions.
The synthesis of polyesters, for example polyethylene
terephthalate, requires the use of catalysts in the
polycondensation step. The literature contains an abundance of
patents describing the use of various catalytically active
substances. Today especially antimony and titanium compounds are
used on a large industrial scale in the manufacturing of
polyethylene terephthalate. This is also reflected in the large
number of patents that describe the use of such compounds.
Polyester-soluble antimony compounds are described in U.S. Pat.
Nos. 3,965,071; 3,998,793; 4,039,515; 4,116,942; 4,133,800;
4,454,312; 5,750,635; and 5,780,575 as polycondensation catalysts.
Modified antimony derivatives (stabilization by substances with
double bonds to prevent reduction to metallic antimony) are, for
example, subjects of U.S. Pat. Nos. 4,067,856; 4,067,857; and
4,130,552. Antimony salts of trimellitic acid esters are likewise
used as catalysts in the manufacturing of polyethylene
terephthalate (U.S. Pat. No. 5,478,796). Titanium derivatives,
especially tetraalkyl titanates, are protected in the U.S. Pat.
Nos. 4,039,515; 4,131,601; 4,482,700; 5,066,766; 5,302,690; WO
97/45470; and U.S. Pat. No. 5,744,571. A combination of sulfonic
acid, titanate and antimony (or germanium) compound is the subject
of U.S. Pat. No. 5,905,136. Germanium compounds are also described
as catalysts for the polycondensation reaction (U.S. Pat. No.
5,378,796; 5,830,981; 5,837,786; and 5,837,800). Catalytically
active compounds in a polycondensation reaction are likewise
borates and acetates of zinc, calcium, cobalt, lead, cadmium,
lithium, or sodium (U.S. Pat. No. 4,115,371).
Defined silicon compounds (2-cyanoethyltriethoxysilane and
3-aminopropyltriethoxysilane) are protected in a US Patent (U.S.
Pat. No. 4,077,944) as polycondensation catalysts.
The combination of several metal compounds is described in the
following patents: U.S. Pat. No. 4,080,317 (Sb/Pb/Zn, Sb/Pb/Ca,
Sb/Zn, Sb/Pb/Mg, Sb/Pb/Ca/Mn, Sb/Pb/Ca/Zn, Sb/Pb/Li, Sb/Mn, Ti/Ca,
Ge/Ga, Ge/Zn, and Ge/K); U.S. Pat. No. 4,104,263
(Sb(Zr)/Zn(Ca,Mn)); U.S. Pat. No. 4,122,107 (Sb/Zn(Ca,Mn)); U.S.
Pat. No. 4,356,299, U.S. Pat. No. 4,501,878, and U.S. Pat. No.
5,286,836 (Ti/Sb); U.S. Pat. No. 4,361,694 (Ti/Si): U.S. Pat. No.
4,468,489 (Ti,Zr,Ge,Zn); U.S. Pat. No. 4,499,226 and U.S. Pat. No.
5,019,640 (Sb/Co); U.S. Pat. No. 5,008,230
(Co(Zn)/Zn(Mn,Mg,Ca)/Sb); U.S. Pat. No. 5,138,024 and U.S. Pat. No.
5,340,909 (Zn/Sb); U.S. Pat. No. 5,565,545 and U.S. Pat. No.
5,644,019 (Sb/Ge); U.S. Pat. No. 5,596,069 (Co/Al); U.S. Pat. No.
5,608,032 and U.S. Pat. No. 5,623,047 (Sb/Co(Mg,Zn,Mn,Pb)); U.S.
Pat. No. 5,656,221 (Sb/Co/Mn); U.S. Pat. No. 5,714,570 (Sb/Ti/Zn);
and U.S. Pat. No. 5,902,873 (Ti(Zr)/lanthanide). At least one
constituent of these complex catalysts is a "classical"
polycondensation catalyst, either antimony, titanium, or
germanium.
Finely dispersed titanates are the subject of U.S. Pat. No.
5,656,716. Jointly precipitated titanium and silicon compounds and
titanium and zirconium compounds are described in U.S. Pat. Nos.
5,684,116 and 5,789,528.
A polycondensation catalyst on the basis of zeolites (alkali or
alkaline earth metal-modified aluminosilicate) is protected in U.S.
Pat. No. 5,733,969. The use of titanium compounds leads to
yellowing of the polyester produced during polycondensation and
processing. Especially during the use of polyethylene terephthalate
as a food packaging, this color is undesirable.
The use of antimony as a catalyst is permitted only within
precisely established boundaries, since this substance, as a heavy
metal, is physiologically problematic.
The goal of this invention is to discover a catalyst system for the
polycondensation, especially of polyethylene terephthalate,
polybutylene terephthalate, or polytrimethylene terephthalate,
which is physiologically safe and makes it possible to use the
polycondensation products for food packaging. In terms of catalytic
activity in polycondensation and selectivity, it must be compatible
with conventional catalysts and must not influence the processing
properties of polyester at all or only to the desired degree.
Quite surprisingly, it was found that complex compounds with
hydrotalcite-analogous structures of the general formula
[M(II).sub.1-x M(III).sub.x (OH).sub.2 ].sup.x+
(A.sup.n-.sub.x/n).mH.sub.2 O, (the use of which was previously
described only as a filler (U.S. Pat. No. 5,362,457; U.S. Pat. No.
5,225,115; JP 09 077,962; JP 02 308,848; JP 61 118,457; JP 56
059,864), in olefin isomerizations, as an adsorbents (halogen
trapper), as a carrier material for catalysts, flame retardant,
molecular sieve, anion exchanger and catalyst for alcohol reactions
(isophorone synthesis), hydrogenations, polymerizations, and
reforming reactions (F. Cavani, F. Trifiro, A. Vaccari, Catalysis
Today 11 (1991), 173-301)), before or after calcination, alone or
in combination with phosphorus compounds that contain at least one
hydrolyzable phosphorus-oxygen compound, are excellently suited for
catalysis of polycondensation reactions, especially for the
production of polyalkylene terephthalate.
In the formula mentioned, M(II) represents divalent metals,
preferably Mg or Zn or Ni or Cu or Fe(II) or Co, and M(III)
represents trivalent metals, preferably Al and Fe, and A represents
anions, preferably carbonates or borates or titanyl compounds.
The particle size of the hydrotalcite used falls in the range of
0.1 to 50 .mu.m, preferably 0.5 to 5 .mu.m.
The calcination of the hydrotalcites can be performed at
temperatures of 200.degree. C. to 800.degree. C., preferably at
400.degree. C. to 650.degree. C.
As phosphorus compounds which contain at least one hydrolyzable
phosphorus-oxygen bond, phosphoric acid esters or esters of
phosphorous acid can be used.
The catalyst system in accordance with the invention is used in the
concentration ratio of hydrotalcite to phosphorus compound of 1:0.5
to 1:4, preferably 1:1 to 1:2.
The untreated or the calcinated hydrotalcite-analogous derivatives
in combination with phosphorus compounds as stabilizers with at
least one hydrolyzable phosphorus-oxygen bond show increased
catalytic activity and selectivity in comparison to conventional
catalysts and are characterized by high food compatibility.
It has been found that these substances, made up of several
components, are highly catalytically selective, relatively
independent of their composition, although the individual
constituents catalyze polycondensation reactions either not at all
or only with a very low selectivity and thus generate a high
fraction of byproducts. It was also found that with the targeted
selection of the constituents, surprisingly it was possible to
influence the applications properties of the polyesters, for
example the crystallization behavior. The polycondensation with the
catalyst system in accordance with the invention is carried out
under vacuum in a liquid phase at temperatures of 230.degree. C. to
280.degree. C. or in a solid phase at temperatures of 170 to
240.degree. C.
The addition of phosphorus compounds with at least one hydrolyzable
phosphorus-oxygen bond leads to improved thermal stability of the
polyesters, especially in the industrially required long residence
times of the liquid polyesters under normal pressure in comparison
to polyesters produced with conventional [catalysts], for example
with catalysts on the basis of antimony and titanium compounds, but
also in comparison to products produced under hydrotalcite
catalysis.
Through the combination of hydrotalcite-analogous
compound/stabilizer, molecular weight degradation and discoloration
of the polyester can be lowered significantly without a negative
influence on other important processing properties of the
polyester, for example the crystallization behavior and the clarity
of the final product.
In the following, the invention will be explained on the basis of
exemplified embodiments.
In a 250-ml, single-necked flask with agitator and distillation
attachment, 100 g precondensate of terephthalic acid and ethylene
glycol with an average molecular weight was placed together with
the catalyst. This apparatus was evacuated to about 0.5 mbar and
purged with nitrogen. This process was repeated a total of three
times. The glass flask was dipped into a hot salt bath at
280.degree. C. and the precondensate allowed to melt at this
temperature. As soon as the melting was complete, vacuum was
carefully applied.
Following termination of the polycondensation by purging with
nitrogen, the product was allowed to cool in the flask, and the
polyester was characterized according to its separation from the
adhering glass.
The intrinsic viscosity (IV) was determined on an apparatus from
the Schott Company (AVSPro) of 250 mg resin dissolved in 50 ml
phenol/dichlorobenzene (1:1).
DSC measurements were performed on a Perkin-Elmer DSC 7.
The acetaldehyde determination took place according to the
following procedure:
The PET material was precooled in liquid nitrogen and ground in an
ultracentrifuge mill. The ground material was immediately weighed
into a headspace vial and closed gas-tight with a septum. After
holding a constant quantity of gas at 150.degree. C. for 90 minutes
in the headspace sampler, the gas was injected onto the GC column,
at a defined pressure. The color numbers were determined with a
LUCI 100 spectrophotometer from the Lange Company.
Table 1 contains characteristic values of polyesters that were
obtained by polycondensation reactions at temperatures of
280.degree. C. using various hydrotalcite catalysts.
TABLE 1 Characterization of polyethylene terephthalate from
polycondensation reactions with various untreated or calcinated
hydrotalcite-analogous derivatives Concentration Reaction time
Acetaldehyde Tg.sup.1 Tc.sup.2 Tcc.sup.3 Tm.sup.4 Experiment no.
Catalyst (ppm) (minutes) IV (dl/g) (ppm) (.degree. C.) (.degree.
C.) (.degree. C.) (.degree. C.) 1 (comparison Antimony (III)
acetate 350 180 0.7480 14.2 79.7 198.9 163.2 248.6 example) 2
(example in Al--Mg-hydrotalcite (acc. 100 180 0.5648 14.4 78.9
197.1 143.5 254.3 acc. with the to U.S. Pat. 5,437,720); invention)
calcinated (18 hours, 450.degree. C.) 3 (example in
Al--Mg-hydrotalcite (acc. 250 165 0.7350 20.7 81.5 184 153.5 251.7
acc. with the to U.S. Pat. 5,437,720); invention) calcinated (18
hours, 450.degree. C.) 4 (example in Al--Mg-hydrotalcite (acc. 500
150 0.6862 16.7 80.9 183.2 150.8 250.1 acc. with the to U.S. Pat.
5,437,720); invention) calcinated (18 hours, 450.degree. C.) 5
(example in Al--Mg-hydrotalcite (acc. 1000 150 0.8412 17.4 82.5
179.3 154.2 252.9 acc. with the to U.S. Pat. 5,437,720); invention)
calcinated (18 hours, 450.degree. C.) 6 (example in
Al--Mg-hydrotalcite (acc. 1000 90 0.8893 44 84.1 175.2 153.5 252.3
acc. with the to U.S. Pat. 5,437,720) invention) 7 (example in
Zn.sub.6 Al.sub.2 (OH).sub.16 CO.sub.3 *H.sub.2 O 500 180 0.6932
16.4 81.9 185.3 152.8 254.4 acc. with the calcinated (18 hours,
invention) 450.degree. C.) 8*(example in Mg.sub.4 Al.sub.2
(OH).sub.12 (B.sub.3 O.sub.3 (OH).sub.4).sub.2 * 500 210 0.6617
22.2 85.2 207.2 251.6 acc. with the H.sub.2 O calcinated invention)
(18 hours, 450.degree. C.) 9*(example in Mg.sub.4 Al.sub.2
(OH).sub.12 (B.sub.3 O.sub.3 (OH).sub.4).sub.2 * 1000 150 0.7704
19.7 79.3 198.4 144 249.6 acc. with the H.sub.2 O calcinated
invention) (18 hours, 450.degree. C.) 10*(example in Mg.sub.3
ZnAl.sub.2 (OH).sub.12 (B.sub.3 O.sub.3 (OH).sub.4).sub.2 * 1000
165 0.6302 17.3 79.6 189.4 153.5 254.3 acc. with the H.sub.2 O
calcinated invention) (18 hours, 450.degree. C.) 11*(example in
Mg.sub.2 Zn.sub.2 Al.sub.2 (OH).sub.12 (B.sub.3 O.sub.3
(OH).sub.4).sub.2 * 1000 180 0.7031 17.3 82.5 201.8 136.1 251.6
acc. with the H.sub.2 O calcinated invention) (18 hours,
450.degree. C.) 12*(example in MgZn.sub.3 Al.sub.2 (OH).sub.12
(B.sub.3 O.sub.3 (OH).sub.4).sub.2 * 1000 120 0.7608 20.2 84.3
201.1 138.1 255.1 acc. with the H.sub.2 O calcinated invention) (18
hours, 450.degree. C.) 13*(example in Zn.sub.4 Al.sub.2 (OH).sub.12
(B.sub.3 O.sub.3 (OH).sub.4).sub.2 * 1000 135 0.8362 22.8 83.3
200.8 137.4 251.7 acc. with the H.sub.2 O calcinated invention (18
hours, 450.degree. C.) *The specification for producing the
catalyst tested in this example can be found in: A. Bhattacharyya,
D.B. Hall: Materials Synthesis and Characterization, 1997, 139-145.
.sup.1 Glass temperature; .sup.2 crystallization temperature;
.sup.3 cold crystallization; .sup.4 melting point.
Table 1 clearly shows that all tested untreated or calcinated
hydrotalcite-analogous derivatives have catalytic activity. The
synthesized polyethylene terephthalate, depending on the catalyst
used, has different processing-related properties.
An additional important criterion for assessing the suitability of
untreated or calcinated hydrotalcite-analogous derivatives is their
catalytic activity in so-called solid state polymerization
(SSP).
For these experiments, six of the polyesters listed in Table 1 were
subjected to SSP. For this purpose the products were left for 96
hours at 200.degree. C. in a vacuum drying oven. After cooling,
characteristic values relevant for applications technology were
determined.
The results of solid state polymerizations of polyethylene
terephthalate are summarized in Table 2.
TABLE 2 Polyesters from solid state polymerization Concentration IV
(dl/g) after IV (dl/g) Acetaldehyde Tg Tc Tcc Tm No. Catalyst (ppm)
polycondensation after SSP (ppm) (.degree. C.) (.degree. C.)
(.degree. C.) (.degree. C.) 1 Zn.sub.6 Al.sub.2 (OH).sub.16
CO.sub.3 *H.sub.2 O 500 0.6932 1.1891 0.3 84.1 162.8 166.9 249.6
calcinated (18 hours, 450.degree. C.) 2 Al--Mg-hydrotalcite 100
0.5648 0.7755 0.4 82.2 178.6 156.1 253 (acc. to U.S. Pat.
5,437,720); calcinated (18 hours, 450.degree. C.) 3
Al--Mg-hydrotalcite 250 0.7350 0.9549 0.4 83.9 172.9 161.5 253
(acc. to U.S. Pat. 5,437,720); calcinated (18 hours, 450.degree.
C.) 4 Al--Mg-hydrotalcite 500 0.6862 1.0775 0.3 83.1 166.2 161.5
249.6 (acc. to U.S. Pat. 5,437,720); calcinated (18 hours,
450.degree. C.) 5 Al--Mg-hydrotalcite 1000 0.8412 1.1005 0.3 84.4
170.9 162.8 252.3 (acc. to U.S. Pat. 5,437,720); calcinated (18
hours, 450.degree. C.) 6 Al--Mg-hydrotalcite 1000 0.8893 1.301 0.9
84.6 176.7 155.5 253.2 (acc. to US Patent 5,437,720) 7 Mg.sub.3
Al.sub.2 (OH).sub.12 (B.sub.3 O.sub.3 (OH).sub.4).sub.2 * 500
0.6617 0.8509 0.6 83.5 201.4 140.8 253.0 H.sub.2 O calcinated (18
hours, 450.degree. C.) 8 Mg.sub.3 Al.sub.2 (OH).sub.12 (B.sub.3
O.sub.3 (OH).sub.4).sub.2 * 1000 0.6302 0.8009 0.6 82.7 179.2 161.5
254.4 H.sub.2 O calcinated (18 hours, 450.degree. C.)
Table 2 shows the fundamental suitability of the untreated or
calcinated hydrotalcite-analogous derivatives as catalysts for
polycondensation reactions in both liquid and solid phase.
It is especially important that it is possible by selecting the
constituents of these complex catalysts to systematically influence
the process technology properties of the polyester resins, for
example the crystallization behavior.
The use of the hydrotalcite catalysts in accordance with the
invention in combination with phosphorous compounds which contain
at least one hydrolyzable phosphorus-oxygen bond is described in
the examples that follow.
EXAMPLE 14 (COMPARISON EXAMPLE)
In a 200 liter reactor of alloyed steel, a suspension of 60.675 kg
terephthalic acid and 1.44 kg isophthalic acid were placed in 31.6
kg ethylene glycol. Under agitation, this reaction mixture was
treated with 45.5 g antimony triacetate and 8.125 g cobalt acetate
tetrahydrate in 1000 g ethylene glycol, and 34.65 g
tetramethylammonium hydroxide in 500 g ethylene glycol. The closed
reactor was heated to 272.degree. C. At 2.8 bar the slow expansion
of the pressurized container was started. After about 20 minutes
under normal pressure, 12 g phosphoric acid in 500 g ethylene
glycol were added. Then the liquid phase polymerization was started
by slow application of the vacuum. After about 60 minutes the final
vacuum of about 4 mbar was reached. The end of the reaction was
shown by the attainment of a defined rotary momentum. The reaction
vessel was relaxed with nitrogen, and the reactor emptied through
several nozzles over a period of about 60 minutes into a water
bath. The product strands were immediately granulated.
The molecular weight and the color of various product batches were
determined.
Table 3 gives a survey of the values determined.
EXAMPLE 15 (COMPARISON EXAMPLE)
In an apparatus in analogy to Example 14, the same amount of
terephthalic and isophthalic acid as well as ethylene glycol,
tetramethylammonium hydroxide, and cobalt acetate tetrahydrate were
placed as in Example 14. After the esterification was complete,
under a slight vacuum 20 g Pural (hydrotalcite with about 60
percent magnesium) were added. The addition of phosphoric acid was
not performed. The liquid phase polycondensation was performed and
ended in the manner described in Example 14.
EXAMPLE 16 (EXEMPLIFIED EMBODIMENT)
In an apparatus analogous to Example 14, a polycondensation was
performed under the same conditions and with the same additives as
in Example 15, but without isophthalic acid. Along with the
hydrotalcite Pural (20 g), 80 g Irganox 1425 (phosphoric acid
ester-based stabilizer from Ciba Geigy) was added to the reaction
mixture.
Table 3 contains characteristic values for individual granulate
fractions.
EXAMPLE 17 (EXEMPLIFIED EMBODIMENT)
Analogous to Example 16, but with the quantity of isophthalic acid
given in Example 14, 20 g Pural, and 20 g Irganox 1425.
Characteristic values of the granulate fractions are contained in
Table 3.
EXAMPLE 18 (EXEMPLIFIED EMBODIMENT)
Analogous to Example 17, but with 20 g Pural and 40 g Irganox
1425.
The characteristic values determined for individual product
fractions are summarized in Table 3.
EXAMPLE 19 (COMPARISON EXAMPLE)
Analogous to Example 17, but with 20 g Pural and 40 g Irgafos
168.
Characteristic values of the granulate fractions are contained in
Table 3
EXAMPLE 20 (EXEMPLIFIED EMBODIMENT)
Analogous to Example 17, but with 20 g Pural and 40 g Irganox
PEPQ.
TABLE 3 Characteristic values of various polyester fractions as a
function of the catalyst-stabilizer system used. Intrinsic Product
Catalyst Stabilizer viscosity a - IV B* - color a - color
Experiment fraction no. Catalyst concentration (ppm) Stabilizer
concentration (ppm) dl/g) (dl/g) number number Example 14 1
Antimony 640 0.69 0.035 1.08 1.12 (comparison 4 triacetate 0.655
3.2 example) Example 15 1 Hydrotalcite 250 0.7051 0.093 0.53 4.82
(comparison 4 0.6113 5.35 example) Example 16 1 Hydrotalcite 250
Irganox 1000 0.6463 0.021 -4.61 2.5 (exemplified 6 1425 0.6251
-2.11 embodiment) Example 17 1 Hydrotalcite 250 Irganox 250 0.674
0.068 -0.31 3.73 (exemplified 5 1425 0.606 3.42 embodiment) Example
18 1 Hydrotalcite 250 Irganox 500 0.683 0.046 -2.54 3.2
(exemplified 5 1425 0.637 0.66 embodiment) Example 19 1
Hydrotalcite 250 Irgafos 500 0.6848 0.073 1.98 1.83 (comparison 5
168 0.6118 3.81 example*) Example 20 1 Hydrotalcite 250 Irganox 500
0.672 0.048 -2.32 3.03 (exemplified 5 PEPQ 0.624 0.71 embodiment)
*Given as "exemplified embodiment" in text.
Tables 2 and 3 illustrate the advantages of hydrotalcites as
catalysts for polycondensation reactions. Hydrotalcites at
substantially lower concentrations have the same catalytic
effectiveness as conventional polycondensation catalysts such as
antimony compounds. In combination with the excellent food
compatibility, with this new class of polycondensation catalysts an
excellent alternative is provided to the currently commercially
utilized catalytically active compounds.
The combination hydrotalcite/phosphoric acid ester or phosphorous
acid ester permits the synthesis of polyesters with a very high
thermal stability. The molecular weight breakdown during processing
listed in Table 3 is more favorable than in the case of the
polyesters produced under antimony catalysis.
In addition, the products are characterized by a low color
tint.
The combination hydrotalcite/phosphoric acid ester or phosphorous
acid ester can also used for the synthesis of other polyesters and
for insertion of other monomers into polyalkylene terephthalate
* * * * *